Non-lubricated, air-actuated, pump-operating, shuttle valve arrangement, in a reciprocating pump

Abstract

A pilot spool is interposed between the compressed air supply and the diaphragm pump-operating main spool, to insure that, at any one time, only one end of the bore in which the main spool reciprocates receives the compressed air. The pilot spool has an annular recess of a length which does not bridge across passageways which admit the air to the main spool, so alternatively, each passageway opens onto an end of the main spool bore. The reciprocating pump structure, that is, the double diaphragms, shaft, and clamp plates, cause the pilot spool to shift, to communicate one of the passageways, with each shift, with the air supply and the main spool bore. No lubrication is provided or needed, and the pilot spool insures that the main spool will not stall.

We claim: 
     
       1. A non-lubricated, air actuated, pump-operating, shuttle valve arrangement, in a reciprocating pump, comprising: a pump housing having a first bore and a second bore formed therein;   a pump-operating shuttle valve slidably disposed in said first bore;   a source of energized air;   a first passageway, formed in said housing, for conducting air from said source to one end of said first bore;   a second passageway, formed in said housing, for conducting air from said source to the opposite end of said first bore;   reciprocating means, interposed between said source and said passageways, for preventing an operative stall of said shuttle valve due to a dead centering thereof, in said first bore, substantially equidistant from said one and said opposite ends of said first bore, said reciprocating means comprising a spool slidably disposed in said second bore, said spool having unitarily formed extended portions at opposite ends thereof; and   translating pumping means within said housing, said pumping means, during translation thereof, engaging said unitarily formed portions of said spool, alternatively, causing reciprocation of said spool.   
     
     
       2. A shuttle valve arrangement according to claim 1, wherein: said spool has an annular recess, formed therein, of a given length, which is in constant communication with said source;   said passageways have terminations which open into said second bore; and   said passageway terminations are spaced apart at a distance greater than said given length to insure that said recess, and said source, open into communication with only one of said passageways at any given time.   
     
     
       3. A shuttle valve arrangement, according to claim 1, further including: sealing means, interposed between said spool and said second bore, for forming variable volume chambers at opposite ends of said second bore.   
     
     
       4. A shuttle valve arrangement, according to claim 3, further including: third and fourth passageways, formed in said housing, and opening onto said second bore, for venting air from said housing.   
     
     
       5. A shuttle valve arrangement, according to claim 4, wherein: said third and fourth passageways open onto opposite ends of said second bore, and onto said chambers, for communication with said first and second passageways.   
     
     
       6. A shuttle valve arrangement, according to claim 5, wherein: said spool comprises opening and closing means cooperative with said second bore for alternatively opening and closing communication of said one and said opposite ends of said first bore, coincident with reciprocation of said spool, with said third and fourth passageways.